Metal cleaning compound



Patented 1, 1932 'rs 'r oF-Flca f swam JONES, or'cmmnen, nasmnusms urn.cI-miime oonom 1m m'wis Application am September 1, 1m, Serial Io.818,115. 'Beuewed January 8, was.

This invention relates to improvements in metal cleaning and morepartlcularly to the.

- It is an ob ect of t 's inventlon to provlde removal of tarnish fromarticles of silver.

Hitherto, one of the most widely used I 5 methods of cleaning goldorsilver articles has been by the use of abrasives, either alone orincorporated in a paste or cloth by means of tallow or other grease.Such abrading process is necessarily slow and has the disadvantage. ofabrading or removing a pot-- .tlon of the metal surface as well as thetar-- nish.' A further disadvantage resides in the fact thatit is verydiflicult or almost impossible to cleandepressed portions" of embossedor en avedarticles. v 'Another met ed in wide use-is that of dissolvingthe tarnish in strong, hot so1utiens of cyanides.' Cyanides, as is wellknown, are extremely oisonous, andcannot be 'handledwith sa ety in theordinary household. Further, any carelessness m washing off the cleanedarticles aftertreat ment might result in the ,fatal .poisoning of anyoneusing them. In addition, the 'well known. solvent action of cyanides forsilver, 'in the presence of air, is a factor to be taken into account.The most commonly used method is to immerse the article to be cleaned ina boil- 3 ing alkaline solution, such as a solution of sodium carbonate,sodium bicarbonate or tri-" sodium phosphate, contained 'in an aluminumpot or like vessel. Ordinary salt may be added to speed up theelectrochemical action.- The article to be cleaned must be in electricalcontact with the aluminum, either directly or through another piece ofmetal, so' that an electric current can flow o from the metal to becleaned to-the aluminum and back to the metal through the elec- Itrolyte; This combination forms a short-cir--. .cuit-ed electrolyticcell in which the alumi .num dissolves electrolytically and the sulfideof the tarnished metal is reduced electrochemically to the metal. Thesulfide ion liberated unites with the hydrogen. set free to form gaseoushydrogen sulfide. Hydro gen-sulfide has an offensive odor. This old 6omethod of cleaning silver leaves themetal jects by providing a com themetal to ing action thereon. I have found that tosea composition ofmatter .which is adapted to i, remove tarnish from metals, and one which5 does not require the articles-tobe cleaned to be im.mersed therein. It1s a further object of this invention to provide a. compositlon ofmatter which is 'acla ted to remove tarnish from metal and w toslmultaneously neutralize or combine with the hydrogen -sulfide asliberated. "L vAnotherobject of tl lis invention is toprovideacomosition of matter which does not comprise alies or other-caustic,or'poisom' a ous substances and is adapted todetamish metals. r f

, Yet another object "of. this invention is to i 1 provide such acomposition of matter as a vendiblearticle, either as a powder, paste,

. or incorporated in a cloth or the like.

I accomplish thwe and other desirable obsition of matter comprising afinely divi ed metalin comoracid salt whose aqueous solution m an acidreaction to litmusfltvith or wlthout a neutral-salt, with or without ananti-odor,

'- and with or without an abrasive, put up either as a, powder, or apaste, or incor orated in a cloth or the like, and adaptedto e activatedwhenwetr v 1 In the manufacture of the composition comprising myinvention '1 use a metal which 4 -I 5 is. sufiicientlyeelectropositivewith respect to 5 Q cleaned as to have a detarnis'hcure the best resultsthe metal should be' finely divided, or pulverized if possible. As"

theresult of protracted experiments, I have found that the followingmetals are suitable for use "in a composition for detarnishing silver orother tarnishable metals or alloys, 1 when taken in conjunction with theacids and acid salts to behereinafter referred to. The metals, in theorder of their reducing power, are: magnesium,- zinc, manganese,-cadmium, iron and aluminum. It will, of course, be readily understoodthat other metals having the desired characteristics may bin'atlon wltha substantially anhydrous acid. 6

be used, and the foregoing are given merely b way of illustration. Thefactors of availa ility of materials, cost, ease of processing(grinding, mixing),-stability', reducing power, and hardness enter intothe choice of the particular metal to be used,'and such choice will bereadily made by those skilled in the art for any given set ofconditions.

- In combination with any of the foregoing metals, I make use of asuitable acidor acid salt whose aqueous solution gives an acid reactionto litmus. As I have mentioned above, the particular acid or acid saltchosen must be-readily soluble in water, non-poisonous, non-hydroscopic,commercially available at a moderate price,andofmoderatestrength. If itis to be part of the powder, paste or cloth sold, it must be in thesolid form. If it is intended for household use it may be a liquid. Foruse in powder form acid salts are preferred, since their solutionscombine good electrical conductivity. with moderate acidity andtherefore give rapid detarnish- {1mg action without excessive generationof eat. 7

. After'numerous experiments, I have found that the following compoundsgive very satisfactory results in conjunction with the metalliccomponents heretofore described. These com ounds are iven by way ofillustration on y, as it will that I may use any compound having likecharacteristics without departing from the spirit of my invention. Thepreferred compounds are. as follows; citric acid, tartaric acid,benzoicacid, salicylic acid, sodium acid citrate, potassium acidcitrate, sodium acid tartrate, potassium-acid tartrate and monosodiumdihydrogen phosphate.

I have also found that the acid .or acid salt may be omitted entirelyfrom the composition in order to avoid any premature reaction betweenthe components. In this case the user can obtain the desired result byadding any appropriate acid solution to the composition at the time ofuse. I find that that vinegar, lemon juice, sour milk and likeacidulated compositions are suitable for use. with the finely dividedmetals above mentioned. These acid materials are available in everyhousehold," and are of relatively low is then taken and the whole isintimatelymixed in a suitable machine such as a ball mill, or the like;To prevent any undesirable premature reaction between the components,

I carry out the grinding and mixing operations under substantially dryconditions. After such treatment, the resulting mixture be readilyapparent used.

is packaged or otherwise prepared, as will be described more fullyhereinafter.

If it is desired to improve the electrical conductivity of the film ofliquid on the surface of the metal being cleaned es eciall where a weakacid is being used, I-a d a sa t to the above described'mixture. 'I findthat practically any cheap, non-poisonous, nonhydroscopic, easilysoluble neutral salt may be used. Sodiumchloride is the cheapest andmost readily available, although I secure eflicient results by the useof any ofsodium citrate, sodium tartarate, or sodium sulfate. It

will be readily apparent that any salt having the desiredcharacteristics can be made use of in the compositions which I havedescribed. Wherean im roved polish is desired, I incorporate an a rasivein the composition.

The abrasive selected must be both soft and chemically inert. I refertouse infusorial earth or some other orm of-silica, although it is tobe. understood that any suitable material may be used.

The salt and abrasive, where used, may be incorporated in the mixtureduring the grinding and mixing operations, or may be added after thesesteps have been accomplished.

compound, or any suitable chemical reagent which will react with thehydrogen sulfied as it is formed, Another method of eliminating the odorof hydrogen sulfide. is the addition of a masking perfume-such as anessential oil orithe like odoriferous' compound.

To accom lish the removal of the hydrogen sulfid incorporate with themetal-acid composition a small quantit of a substance which is adaptedto react wit the gas to form an odorlesg; compound which has nodeleterious eflect n the surface of themetal under treatment, I havefound that the metals or.

their oxidts which form sulfides insoluble in dilute aci are effectivein preventing the escape of ydrogen sulfide, and thus act as ananti-odcir. I- prefer to use copper oxide in .finely divided form,although other metals or their oxides having thedesired properties suchas lead or bismuth, for instance, can be As mentiq ned above inthecas ofthe salt and abrasive additions to the mixture, the anti-odor may beground up with either of the reacting components, or preliminarilyground and added-in the mixing stage.

The follpw'ing ate preferred examples of compositions which are suitablefor use in the powdered form:

Zinc 33.3 Sodium acid tartrate 100.0 Copper oxide 8.4

substantially dry, powdered;

In use, the

metal, acid or mixture of an electropositive acid salt, with or withoutan of'the neutral salt, anti-odor or abrasive, a ove mentioned, issprinkled on a damp cloth and applied to 5 1 the artlcle to be cleaned.The operation is very easily performed. There are no caustic alkalinematerials or strong acids to corrode the hands of the user; there is noboiling up of the electrolyte; and the articles after cleaning merelyrequire a simple rinsing in tap water to remove thereagents or they canbe wiped with a damp cloth.

As noted previously, the acid or acid salt may be omitted from thecomposition and lemon juice, sour milk), can be used to dampen the clothupon'which the other ingredients are. sprinkled. the fundamentalelectrochemical reactions being unchanged.

The powdered composition can in anysuitable manner. taken to have thepackage substantially ai'r' tight to prevent access of moisture .to theingredients. For. export trade, which'are excessively damp, it maybedesirable to omit the acid. or acid salt from the composition, the usersupplying such omission in the manner designated. .As examples bepaekaged o of suitable forms of packages may be men- P g 1 tioned thecans used for ispensm tooth- W111110W be argum nt ha I v p cleaningpowders and the hermetical. y sealed f 8 9 2"! which 5 adapted forglassine packets or envelopes. i use 1n the detarmshmg ot metals, andone c Any of the powder compositions made ac- Wi h v ate he ne s ty o1151112 Q cording to my invention maybe incorporated p a p tu r, e Thein a suitable water-soluble vehicle to form 'a D W f 9PNt10n ln dfreedom from odorspaste, and the resulting product ut up in and m sslneyhlchj harap rlz s h s jars or collapsible tubes. Thevehici; or bindiQWDO OD' ompri d lf h er used for carrying the powdered ingredi- P 1 112 o y Yfi 15 a ents, prepared as above described, is inoor o- 'tmctadvanceover the practice of the pr or in any suitable machine, or theingredients may be wet-ground in the vehicle or binder. care bein takento exclude moisture. As will be read y understood, the vehicle or hinderused for carrying the powdered ingredients should be a non-aqueous,non-ionizin liquid, having a minimum 0 solvent action on ,-theaci d oracid salt used, and'be readily miscible with water so-that go. it maywork by dilutiontherewith, I have found that denatured alcoholand'glycerine are suitable vehicles, but I wish it to be understoodthatthese are merely illustrative since other materials having the desiredcharac- 66 'teristics may be u rated therewith mixture to the as,starch, dextrine or any of the materials mentioned (vinegar,

Care should he or for localities Soap has been widely used as'a vehiclefor carrying owdered materials which are to be used as a rasives or thelike, but I find that it is not suitable for the purpose of myinvention.This is due to the fact that the use of soap leaves an infinitelythin'saponaceous film on the cleaned metal, which film exerts adeleterious effect on the metal and facilitates further tarnishing.

Where it is desired to impregnate a cloth, paper or like fibrousmaterial with any of the compositions set forth I mix a water solublegum, such as Karachi gum, the metal and a neutral cloth in'a machineknowntto the textile industry as a padder. The water is removed fromthelfabricbyeyaporation. The acid or acid saltis dissolved in a suitablenon-ionizing solvent such as denatured alco- ';hol and the resultingsolution is applied to the prepared fabric. The aleohol'is removed withsolvent recovery. Iuplace of the Karachi gum I may use equivalentmaterials, such other carbohydrate gums.

As with the powder and the paste modifications of my invention, the acidor acid salt salt with water and apply the may be omitted from theimpregnating composition used in connection with the fabric, and the"latter moistened with an appropriate acidulated solution at the time ofuse. As already noted, vinegar. lemon juice, or sour milk are suitablefor this purpose. These materials have been given by way of exampleonly, and 'it is obvious that any suitable fruit juice or the like maybe used.

The impregnated fabric can be cut to any suitable size and out up inmoisture-proo art.

-Wh. l -1I ism disclosed preferred embodimen sot inn-invention. I wishit to be understood-"that these-are but preferred embodimerits whichtvpifv others in which may be incorporated the underlying features'of'this f -invention. Modifieations1 .m avbe made in the proportions ofthe incredients used, withof matter for cleaning agent adapted to forminodorous compounds with the. odorous reaction products.

2. A composition of matter for cleaning metal, comprising an intimatemixture of a metal. an acid salt whose aqueous solution gives an acidreaction, and a chemically reactive agent adapted to form inodorouscompounds with the odorous reaction products.

3. A composition of matter for cleaning metal, comprising an intimate ofa metal, an acid, a chemically reactive agent adapted to form inodorouscompounds with the odorous reaction products, and an abrasive. Y 1

4. A composition of matter comprising an intimate m xture of a metal, anacid salt whose aqueous solution gives an acid reac-' tion, a'chemicallyreactive agent adapted to form inodorous compounds with the odorous mreaction products, and an abrasive.

5. A composition of matter comprising an intimate'mixture-of a metanacid saltwhose aqueous solutiongives ;an acid reaction, a chemicallyreactive agent adapted to a form inodorous compounds with the odorousreaction products and an abrasive, the whole being finely'divided andincorporated in a non-saponaceous water-soluble binder. 6. An article ofmanufacture, comprising an intimate and potentially reactive mixture ofa metal and an acid salt whose aqueous solution gives an acid reactionbound tosilver, compris' an intimate (Potentially reactive mixture c ametal an a solid acidreactin material.

14. v composition of matter for cleaning silver, comprising an intimate(potentially reactive mixture of a metal an a solid acid, the. wholebeing finely divided.

i 15. A composition of matter comprising an intimate and potentiallyreactive mixture of magnesium and sodium hydrogen tartrate.

In testimony whereof I aflix my si ature.

" GRINNELL J O S.

gether' by a non-saponaceous water-soluble v inder and put u in pasteform.

7. An article 0 manufacture, comprising an intimate mixture of a metal,an acid salt whose aqueous solution gives an acid reaction and achemically reactive agent adapted to form inodorous compounds with theodor- 4o ous reaction products bound to ther by a non-saponaceouswater-soluble put n2 in .pasteform.

8. composition of matter for cleaning metal, comprising an intimate andpotentially-reactive mixture of magnesium and a crystalline acid. l

9. A composition of matter for cleaning metal, comprising an intimateand potentially reactive mixture of magnesium and an an drous acid. t

A composition of matter,'comprisin an intimate mixture ofmagnesium, anaci salt whose aqueous solution givesan acid reaction, and a chemicallyreactive agent I adapted to form, inodorous compounds with.

the odorous reaction products.

11. A. composition of matter, comprisin an intimate mixture ofmagnesium, an aci salt, and copper oxide. 12.. A metal cleaningcomposition comprising finely divided magnesium, having incorporatedtherewith a substantially dry acid salt whose aqueous solutiongives anacid reaction and copper oxide.

ea 13. A composition of matter tor clieaning mder and

